多电平PWM控制技术发展

多电平PWM控制技术一直是多电平变换器研究的核心内容之一。基于传统两电平PWM技术研究的经验，经过近十几年的发展，多电平PWM控制技术已形成了儿类不同的实现方法，同时新的控制方法还在涌现。与两电平相比，多电平PWM方法需要面对一些新出现的问题，并拓展PWM控制的内涵，进而形成新的PWM控制思路。按照目前的发展情况，多电平PWM控制方法一般有多电平载波PWM方法、多电平空间矢量PWM方法，以及其他优化的PWM方法。本文对已有多电平PWM控制技术进行了归纳和分析，最后指出多电平空间矢量法和载波调制法在一定条件下具有内在的一敛性。     

工业牵引应用的采用软穿通IGBT技术的大功率模块

随着采用1700V-SPT（软穿通）IGBT LoPak密集型封装结构模块类型，和为了进一步开发利用新的1700V—SPT IGBT和二极管芯片的特性，出现了新的封装类型的模块：即电压1700V，电流额定值为2400A，封装形式为“E1”和“E2”工业标准模块。我们在长期高可靠性应用的经验基础上，设计了新的封装类型，其特性适用于牵引市场。在本文中，讨论了1700V—SPT IGBT（E1／E2）模块范围的特性，尤其论述了改进的静态和动态特性。     

应用于工业牵引的软穿通IGBT技术的大功率模块

随着1700V-SPT（软穿通）GBT LoPak密集型封装结构模块类型的引入，为了进一步开发利用新的1700V-SPT IGBT和二极管芯片的特性，出现了新的封装类型的模块：即电压1700V，电流额定值为2400A，封装形式的E1和E2工业标准模块。我们在长期高可靠性应用的经验基础上，设计了新的封闭类型，其特性适用于牵引市场。在本文中，讨论了1700V-SPT国IGBT（E1/E2）模块范围的特性，尤其论述了改进的表态和动态特性。     

Unidimensional Modulation Technique for Cascaded Multilevel Converters

This paper presents a simple and low-computational-cost modulation technique for multilevel cascaded H-bridge converters. The technique is based on geometrical considerations considering a unidimensional control region to determine the switching sequence and the corresponding switching times. In addition, a simple strategy to control the dc-voltage ratio between the H-bridges of the multilevel cascaded converter is presented. Examples for the two-cell topology are shown, but the proposed technique can be applied to develop modulation methods for a higher number of H-bridges. Experimental results are presented to validate the proposed technique.      

Remote Laboratory for Experimentation With Multilevel Power Converters

This paper describes the hardware and software modules of a remote Internet-based laboratory for experimentation with a 120-kVA multilevel power converter. The key feature of this laboratory is the utilization of a multilevel converter that can be controlled and supervised remotely in a secured way. A wide variety of laboratory experiments are supported, from grid connection to ac motor control. Users can choose the control structure, the control parameters, and the kind of load and get the graphical results of the measurements, all in real time.      

直流变换器软开关技术综述

近几十年来,随着功率密度的提高,DC/DC变换器软开关技术取得了很多成就。从谐振变换器、软开关-PWM变换器以及移相全桥软开关变换器三个方面对直流软开关技术进行了综述,比较了各种软开关技术的优缺点;对进一步提高软开关变换器效率的改进方法进行了展望。     

多电平逆变器直流侧电压平衡控制策略综述

针对这种在输出有功功率时直流侧电容电压不平衡的问题,介绍了用于二极管箝位五电平逆变器的四种基于电容的辅助稳压电路：基于单级电容的辅助稳压电路、通用直流辅助稳压电路、单电容辅助稳压电路和简化的单电容辅助稳压电路,和三种基于电感的辅助稳压电路,详细说明了每一种电路的电路结构、脉冲宽度调制控制策略以及工作原理,并通过MatIab／Simuljnk仿真验证了控制结果。     

Modified Phase-Shifted PWM Control for Flying Capacitor Multilevel Converters

The issue of voltage imbalance remains a challenge for the flying capacitor multilevel converter. The phase-shifted pulsewidth modulation (PS-PWM) method has a certain degree of self-balancing properties. However, the method alone is not sufficient to maintain balanced capacitor voltages in practical applications. The paper proposes a closed-loop modified PS-PWM control method by incorporating a novel balancing algorithm. The algorithm takes advantage of switching redundancies to adjust the switching times of selected switching states and thus maintaining the capacitor voltages balanced without adversely affecting the system's performance. Key techniques of the proposed control method, including selection of switching states, calculation of adjusting times for the selected states, and determination of new switching instants of the modified PS-PWM are described and analyzed. Simulation and experimental results are presented to confirm the feasibility of the proposed method     

Numerical Optimization of an Active Voltage Controller for High-Power IGBT Converters

Feedback control of insulated gate bipolar transistors (IGBTs) in the active region can be used to regulate the device switching trajectory. This facilitates series connection of devices without the use of external snubber networks. Control must be achieved across the full active region of the IGBT and must balance a number of conflicting system goals including diode recovery. To date, the choice of control parameters has been a largely empirical process. This paper uses accurate device models and formalized optimization procedures to evaluate IGBT active voltage controllers. A detailed optimization for the control of IGBT turn-on is presented in this paper     

Modeling Strategy for Back-to-Back Three-Level Converters Applied to High-Power Wind Turbines

Three-level converters are becoming a realistic alternative to the conventional converters in high-power wind-energy applications. In this paper, a complete analytical strategy to model a back-to-back three-level converter is described. This tool permits us to adapt the control strategy to the specific application. Moreover, the model of different loads can be incorporated to the overall model. Both control strategy and load models are included in the complete system model. The proposed model pays special attention to the unbalance in the capacitors' voltage of three-level converters, including the dynamics of the capacitors' voltage. In order to validate the model and the control strategy proposed in this paper, a 3-MW three-level back-to-back power converter used as a power conditioning system of a variable speed wind turbine has been simulated. Finally, the described strategy has been implemented in a 50-kVA scalable prototype as well, providing a satisfactory performance     

P-I-N Diodes for Low-Frequency High-Power Switching Applications

The development of high-power low-frequency diodes, conditions for their operation, and results measured in actual circuits are described. Harmonic distortion at 500 kHz and 2 MHz has been found to decrease with increasing diode lifetime and forward-bias current. Large reverse bias voltages are necessary at low frequencies to keep the RF voltage swing from penetrating the forward conduction region. The improvement of p-i-n diode lifetimes with thicker I-layers or with planar construction has been studied and the performance of these diodes in a routing switch is reported.     

Curtain Antennas for High-Power HF Broadcasting Applications

The performance of high-power curtain antennas which have been designed for international broadcasting stations is presented along with details of design and construction. The antennas described provide horizontal beamwidths ranging from 190°to 28 °, vertical beamwidths from 4°to 12°, and power gains ranging from 18 to more than 23.5 dB above a half-wave dipole in free space.     

Solving EMI-Related Problems for Reliable High-Power Converters Design With Precomputed Electromagnetic Models

Interactions between low-power control circuits such as DSP or field-programmable gate array (FPGA), and high-power switching components that generate high $partial ihbox{/}partial t$ greatly decrease the reliability of power converters. Moreover, they increase substantially the product's time to market when introducing a new design. The analysis of these couplings is traditionally done by using the finite elements method, which requires high technical expertise for complex 3-D circuit geometries. To overcome this requirement, the authors propose an approach based on the use of a precomputed electromagnetic model (PEM) library, which includes several metallic conducting structures present in modern power converters. Transistor cases, as well as printed circuit board (PCB) copper traces, are included in this library. By using these library models, high-coupling areas with higher flux density can be quickly identified in the converter 3-D layout. This helps to develop a remedial strategy for avoiding higher flux density areas. The proposed approach is used to analyze the electromagnetic behavior of a bidirectional matrix converter cell. Experimental results are also presented to further demonstrate the viability of the new proposed approach.      

军事卫星通信应用中的变频器

在所有的卫星通信系统中,上变频和下变频器件都很关键,其技术参数对整个系统的性能有极大影响.     

Band-Stop Filters For High-Power Applications

There are several advantages to the use of band-stop filters, rather than band-pass filters, in many systems. This is shown to be particularly true when signals at high-power levels must be transmitted or rejected. A formula has been derived which expresses the external Q of each resonator in a band-stop filter in terms of the element values of the normalized low-pass prototype and the parameters of the frequency transformation. The peak power capacity of iris-coupled waveguide cavity filters and TEM filters using capacitively coupled inductive stubs is then determined in terms of the external Q of the first resonator and the dimensions of the resonator. Experimental results given for a waveguide band-stop filter show good agreement with theory.     

Microwave Silicon Windows for High-Power Broad-Band Switching Applications

Theoretical and experimental results obtained with a novel silicon window utilizing double-carrier injection to achieve high-power broad-band microwave switching are presented. The device consists of a wafer of high-resistivity silicon inserted across a waveguide with thin-line junction structures oriented orthogonal to the RF electric field. These line junctions provide hole-injecting contacts on one face and electron-injecting contacts on the other. With zero bias, the window appears as a thin low-loss dielectric slab, and the RF signal is transmitted. With forward bias, the window appears as a highly conductive slab due to the injected electron-hole plasma, and the RF signal is reflected. Calculations show that X-band windows 8 mils thick have a switching ratio of 0.5 to 15 dB if the resistivity change is from 300/spl Omega//spl dot/cm to 1/spl Omega//spl dot/cm. X-band windows have been fabricated having an insertion loss as low as 0.3 dB and a VSWR below 1.3 in the transmission state and an isolation as high as 18 dB (5 amperes at 1 volt) in the reflecting state. These characteristics are maintained across the complete waveguide band (8.2 to 12.4 GHz). Windows have been tested to 50-kW peak power without degradation in switching characteristics. The main advantages of the window over conventional p-i-n diodes are an order of magnitude or more increase in power handling (50 kW peak measured while 300 kW is predicted compared to 5 kW for a single p-i-n diode X-band high-power switch), full guide bandwidth operation (compared to 10 percent bandwidth for the conventional p-i-n), simpler bias circuitry (no reverse bias is required in the transmission state), and higher temperature operation (since no reverse voltage is needed).     

A High-Power High-Voltage DC-DC Converter for Space Applications

The design details of a modular dc-dc converter used to power the main anode supply of a mercury-iron motor are presented. This motor, the RIT-35 built by Messerschmitt-B?lkowBlohm (MBB), Germany, is used as the propulsion unit of a future Asteroid Gravity Optical and Radar Analysis (AGORA) mission. The design selected to cope with the high-voltage high-power conversion for space applications is shown, as well as the requirement to operate from an unregulated solar array with a voltage excursion of from 150 V at beginning-of-mission (BOM) to 240 V at end-of-mission (EOM).     

A Multipulse-Structure-Based Bidirectional PWM Converter for High-Power Applications

Multipulse converters are suitable for high-power application with the merits of low switching frequency and perfect harmonic performance. But less controllability and poor regulation lead the restriction on its application. A bidirectional pulsewidth modulation (PWM) converter based on multipulse structure is proposed in this paper, which has the same perfect harmonic performance with very low switching frequency. A special sequential sampling space vector modulation technique, which has the sampling sequence from the lagging module to the leading module, is proposed to make the converter controllable like conventional PWM converters. The harmonic performance and linear regulation capability are analyzed theoretically. The converter is modeled in detail, and an instantaneous feedback control strategy with phase delay compensation and decoupling control is also proposed. The controller parameters are optimized to get high dynamic performance with adequate phase margin and gain margin. A 3-kVA prototype is built, and the simulation and experiment results validate that the proposed converter is quite suitable for high-power conversion.     

Comparison of 2.3-kV Medium-Voltage Multilevel Converters for Industrial Medium-Voltage Drives

This paper compares the expense of power semiconductors and passive components of a (2.3 kV, 2.4 MVA) two-level, three-level neutral-point-clamped, three-level flying-capacitor, four-level flying-capacitor, and five-level series-connected H-bridge voltage source converter on the basis of the state-of-the-art 6.5-, 3.3-, 2.5-, and 1.7-kV insulated gate bipolar transistors for industrial medium-voltage drives. The power semiconductor losses, the loss distribution, the installed switch power, the design of flying capacitors, and the components of an sine filter for retrofit applications are considered.